title: The origin and loss of the ubiquitin activating enzyme gene on the mammalian Y chromosome.
abstract: Mammalian sex chromosomes are thought to be descended from a homologous pair of autosomes: a testis-determining allele which defined the Y chromosome arose, recombination between the nascent X and Y chromosomes became restricted and the Y chromosome gradually lost its non-essential genetic functions. This model was originally inferred from the occurrence of few Y-linked genetic traits, pairing of the X and Y chromosomes during male meiosis and, more recently, the existence of X-Y homologous genes. The comparative analysis of such genes is a means by which the validity of this model can be evaluated. One well-studied example of an X-Y homologous gene is the ubiquitin activating enzyme gene ( UBE1 ), which is X-linked with a distinct Y-linked gene in many eutherian ('placental') and metatherian (marsupial) mammals. Nonetheless, no UBE1 homologue has yet been detected on the human Y chromosome. Here we describe a more extensive study of UBE1 homologues in primates and a prototherian mammal, the platypus. Our findings indicate that UBE1 lies within the X-Y pairing segment of the platypus but is absent from the human Y chromosome, having been lost from the Y chromosome during evolution of the primate lineage. Thus UBE1 illustrates the key steps of 'autosomal to X-specific' evolution of genes on the sex chromosomes.
authors.affiliation: INSERM U406, Facult-e de M-edecine La Timone, 13385 Marseille, France. mitchell@ibdm.univ-mrs.fr
authors.forename: M J
authors.initials: MJ
authors.lastname: Mitchell
authors.forename: S A
authors.initials: SA
authors.lastname: Wilcox
authors.forename: J M
authors.initials: JM
authors.lastname: Watson
authors.forename: J L
authors.initials: JL
authors.lastname: Lerner
authors.forename: D R
authors.initials: DR
authors.lastname: Woods
authors.forename: J
authors.initials: J
authors.lastname: Scheffler
authors.forename: J P
authors.initials: JP
authors.lastname: Hearn
authors.forename: C E
authors.initials: CE
authors.lastname: Bishop
authors.forename: J A
authors.initials: JA
authors.lastname: Graves
mesh_terms: D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D017931:DNA Primers; D017353:Gene Deletion; D006801:Humans; D008025:Ligases / Q000235:genetics*; D008297:Male; D008322:Mammals; D008969:Molecular Sequence Data; D010802:Phylogeny; D010987:Platypus; D011323:Primates; D011544:Pseudogenes; D044764:Ubiquitin-Activating Enzymes; D044767:Ubiquitin-Protein Ligases; D014960:X Chromosome; D014998:Y Chromosome
chemical_list: D017931:DNA Primers; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; D044764:Ubiquitin-Activating Enzymes